JP5758778B2 - Vehicle and vehicle control method - Google Patents

Description

  The present invention relates to a vehicle, and more particularly to a vehicle that travels using at least one of an engine and a motor.

  In recent years, hybrid vehicles that travel using at least one of the power of an engine and a motor are becoming widespread. Some hybrid vehicles include a generator that generates power by the power of an engine, in addition to a motor.

  Japanese Unexamined Patent Application Publication No. 2007-196733 (Patent Document 1) discloses that in a hybrid vehicle including an engine, a motor, and a generator, when a battery that stores electric power for driving the motor fails, the battery is removed from an electric system including the motor and the generator. There is disclosed a technique for performing control (hereinafter, also referred to as “battery-less travel control”) in which the vehicle is driven by driving the motor with the electric power generated by the generator using the power of the engine.

JP 2007-196733 A JP 2008-72868 A JP 2009-45946 A JP 2008-279978 A

  By the way, an inverter for driving a motor is mounted on the hybrid vehicle. Main control methods of the inverter include a pulse width modulation (hereinafter also referred to as “PWM”) control method and a rectangular wave voltage control (hereinafter also simply referred to as “rectangular control”) method. The rectangular control has a large voltage conversion modulation rate (a value corresponding to the ratio of the output voltage to the input voltage) and can increase the motor output, while the control accuracy (control responsiveness) is inferior to the inverter control. The voltage tends to become unstable. Therefore, generally, rectangular control is used only in the high vehicle speed region, and PWM control is usually used.

  On the other hand, at the time of batteryless travel control, the battery cannot be used as a power buffer, and it is necessary to accurately balance the power balance between the motor and the generator. However, if the vehicle speed range is reached during battery-less travel control, the inverter control method is shifted from PWM control to rectangular control with poor control accuracy. As a result, when a sudden change in required driving force occurs, the balance of power balance is lost, and the voltage (inverter output voltage) applied to the motor may become unstable.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress an unstable voltage applied to a motor during batteryless travel control.

  A vehicle according to the present invention is a vehicle that travels by rotating an output shaft connected to drive wheels using power of at least one of an engine and a motor, and a generator that generates power using power of the engine, and a motor The battery is configured to be connectable to a pair of power lines that electrically connect the generator and the generator, and a control device that controls the motor and the generator. The control device drives the motor with pulse width modulation control when the vehicle speed is less than the threshold value, and when the vehicle speed exceeds the threshold value, the output is improved but the controllability is inferior to the pulse width modulation control. To drive the motor. The control device performs battery-less running control in which the battery is disconnected from the pair of power lines and the motor is driven by the power generated by the generator when the battery is abnormal. When performing the batteryless travel control, the control device generates a voltage so that the voltage between the pair of power lines is higher when the vehicle speed exceeds a reference value corresponding to the threshold value than when the vehicle speed is less than the reference value. And control the motor.

  Preferably, the vehicle includes a first inverter provided between the pair of power lines and the generator to drive the generator, and a second inverter provided between the pair of power lines and the motor to drive the motor. Is further provided. The control device controls the power converter so that the actual voltage between the pair of power lines becomes the target voltage. When performing the batteryless travel control, the control device sets the target voltage to a higher value when the vehicle speed exceeds the reference value than when the vehicle speed is less than the reference value.

  Preferably, the vehicle further includes a transmission provided between the motor and the output shaft. The control device changes the reference value according to the transmission gear ratio.

  Preferably, the transmission forms either a low speed stage or a high speed stage having a lower speed ratio than the low speed stage. The control device makes the threshold value and the reference value larger when forming the high speed stage than when forming the low speed stage.

  Preferably, the vehicle includes a ring gear coupled to the motor, a sun gear coupled to the generator, a pinion gear engaged with the sun gear and the ring gear, and a carrier coupled to the engine and rotatably supporting the pinion gear. Is further provided.

  A vehicle control method according to another aspect of the present invention is a control method for a vehicle that travels by rotating an output shaft connected to drive wheels using at least one of an engine and a motor. The vehicle includes a generator that generates power using engine power, a battery configured to be connectable to a pair of power lines that electrically connect the motor and the generator, and a control device that controls the motor and the generator. As for the control method, when the vehicle speed is less than the threshold value, the motor is driven by pulse width modulation control. When the vehicle speed exceeds the threshold value, the output is improved but the controllability is inferior to the pulse width modulation control. The step of driving the motor at step B, the step of performing battery-less running control in which the battery is disconnected from the pair of power lines when the battery is abnormal, and the motor is driven by the power generated by the generator, and And a step of controlling the generator so that the voltage between the pair of power lines becomes higher than when the vehicle speed is less than the reference value when the reference value corresponding to the threshold value is exceeded.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the voltage applied to a motor becomes unstable during battery-less driving | running | working control.

1 is an overall block diagram of a vehicle. An alignment chart of a power split mechanism and a transmission is shown. It is a circuit diagram of the electric system for drive-controlling 1st MG and 2nd MG. It is a figure which illustrates schematically the control mode of 2nd MG. It is a figure which shows the correspondence of a vehicle operating point and the control mode of 2nd MG. It is a flowchart (the 1) which shows the process sequence of ECU. It is a functional block diagram (the 1) of ECU. It is a flowchart (the 2) which shows the process sequence of ECU.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is an overall block diagram of a vehicle 1 according to the present embodiment. The vehicle 1 includes an engine 100, a first MG (Motor Generator) 200, a power split mechanism 300, a second MG 400, a transmission 500, a propeller shaft (output shaft) 560, a PCU (Power Control Unit) 600, A battery 700, an SMR (System Main Relay) 710, and an ECU (Electronic Control Unit) 1000 are provided.

  The engine 100 is an internal combustion engine that outputs power by burning fuel. The power of engine 100 is input to power split device 300.

  Power split device 300 splits the power input from engine 100 into power to output shaft 560 and power to first MG 200.

  Power split device 300 rotates sun gear (S) 310, ring gear (R) 320, pinion gear (P) 340 meshed with sun gear (S) 310 and ring gear (R) 320, and pinion gear (P) 340. It is a planetary gear mechanism having a carrier (C) 330 that is held to revolve freely.

  Carrier (C) 330 is connected to the crankshaft of engine 100. Sun gear (S) 310 is coupled to the rotor of first MG 200. Ring gear (R) 320 is connected to output shaft 560.

  The first MG 200 and the second MG 400 are AC rotating electrical machines, and function as both an electric motor (motor) and a generator (generator). The power of second MG 400 is input to transmission 500.

The transmission 500 changes the rotational speed of the second MG 400 and transmits it to the output shaft 560.
The transmission 500 is configured by a set of Ravigneaux planetary gear mechanisms. That is, the transmission 500 includes a first sun gear (S1) 510, a second sun gear (S2) 520, a first pinion (P1) 531 meshing with the first sun gear (S1) 510, and a first pinion (P1). 531 and the second pinion (P2) 532 meshing with the second sun gear (S2) 520, the ring gear (R1) 540 meshing with the second pinion (P2) 532, and the pinions 531 and 532 are held rotatably. Carrier (C1) 550. Therefore, the first sun gear (S1) 510 and the ring gear (R1) 540 constitute a mechanism corresponding to the double pinion type planetary gear mechanism together with the pinions 531 and 532, and the second sun gear (S2) 520 and the ring gear (R1). ) 540 and the second pinion (P2) 532 constitute a mechanism corresponding to a single pinion type planetary gear mechanism.

  The carrier (C1) 550 is coupled to the output shaft 560. Second sun gear (S) 520 is coupled to the rotor of second MG 400.

  Further, the transmission 500 is provided with a B1 brake 561 that selectively fixes the first sun gear (S1) 510 and a B2 brake 562 that selectively fixes the ring gear (R1) 540.

  The B1 brake 561 generates an engagement force by the frictional force between the friction material fixed to the case side of the transmission 500 and the friction material fixed to the first sun gear (S1) 510 side. The B2 brake 562 generates an engagement force by the frictional force between the friction material fixed to the case side of the transmission 500 and the friction material fixed to the ring gear (R1) 540 side. These brakes 561 and 562 are connected to a shift hydraulic circuit (not shown) that outputs hydraulic pressure according to a control signal from the ECU 1000, and are engaged by hydraulic pressure output from the shift hydraulic circuit. Or be released.

  When the first sun gear (S1) 510 is fixed by engaging the B1 brake 561 and the ring gear (R1) 540 is not fixed by releasing the B2 brake 562, the transmission speed of the transmission 500 is set to the high speed Hi. Become. On the other hand, when the ring gear (R1) 540 is fixed by engaging the B2 brake 562 and the first sun gear (S1) 510 is not fixed by releasing the B1 brake 561, the transmission speed of the transmission 500 is the high speed. The low speed stage Lo has a gear ratio larger than Hi. The gear ratio is the ratio of the input shaft rotation speed (= second MG rotation speed Nm2) to the output shaft rotation speed of the transmission 500 (= the rotation speed Np of the output shaft 560).

  Output shaft 560 is rotated by at least one of the power of engine 100 transmitted through power split device 300 and the power of second MG 400 transmitted through transmission 500. The rotational force of the output shaft 560 is transmitted to the left and right drive wheels 82 via the speed reducer. Thereby, the vehicle 1 travels.

FIG. 2 shows an alignment chart of power split mechanism 300 and transmission 500.
By configuring the power split mechanism 300 as described above, the rotational speed of the sun gear (S) 310 (= first MG rotational speed Nm1), the rotational speed of the carrier (C) 330 (= engine rotational speed Ne), the ring gear ( R) The rotational speed of 320 is a relationship that is connected by a straight line on the alignment chart of power split mechanism 300 (a relationship in which the remaining rotational speed is determined if any two rotational speeds are determined).

  Further, by configuring the transmission 500 as described above, the rotational speed of the first sun gear (S1) 510, the rotational speed of the ring gear (R1) 540, the rotational speed of the carrier (C1) 550, the second sun gear (S2). ) The rotational speed of 520 (= second MG rotational speed Nm2) is connected in a straight line on the alignment chart of the transmission 500 (a relation in which the remaining two rotational speeds are determined if any two rotational speeds are determined). Become.

  Since the carrier (C1) 550 of the transmission 500 is connected to the output shaft 560, the rotational speed of the carrier (C1) 550 matches the rotational speed of the output shaft 560 (that is, the vehicle speed V). Further, since the ring gear (R) 320 of the power split mechanism 300 is also connected to the output shaft 560, the rotational speed of the ring gear (R) 320 also matches the rotational speed of the output shaft 560 (that is, the vehicle speed V).

  At the low speed stage Lo, the B2 brake 562 is engaged and the ring gear (R1) 540 is fixed, so the rotational speed of the ring gear (R1) 540 becomes zero. Further, at the high speed stage Hi, the B1 brake 561 is engaged and the first sun gear (S1) 510 is fixed, so the rotational speed of the first sun gear (S1) 510 becomes zero. Therefore, when the second MG rotation speed Nm2 is the same, as shown in FIG. 2, due to the relationship between the collinear line (one-dot chain line) of the high speed stage Hi and the collinear line (solid line) of the low speed stage Lo, the high speed stage Hi. The vehicle speed V at the time of formation becomes higher than the vehicle speed V at the time of formation of the low speed stage Lo. On the contrary, when the vehicle speed V is the same, as shown in FIG. 2, the high speed stage Hi is formed due to the relationship between the collinear line (two-dot chain line) of the high speed stage Hi and the collinear line (solid line) of the low speed stage Lo. The second MG rotation speed Nm2 at the time becomes lower than the second MG rotation speed Nm2 at the time of forming the low speed stage Lo.

  Returning to FIG. 1, PCU 600 converts high-voltage DC power supplied from battery 700 into AC power and outputs the AC power to first MG 200 and / or second MG 400. Thereby, first MG 200 and / or second MG 400 is driven. PCU 600 converts AC power generated by first MG 200 and / or second MG 400 into DC power and outputs the DC power to battery 700. Thereby, the battery 700 is charged.

  Battery 700 is a secondary battery that stores high-voltage (for example, about 200 V) DC power for driving first MG 200 and / or second MG 400. The battery 700 typically includes nickel metal hydride and lithium ions. Note that a large-capacity capacitor may be used instead of the battery 700.

  The SMR 710 is a relay for switching the connection state between the battery 700 and the electric system including the PCU 600.

  The ECU 1000 is connected to the engine rotational speed sensor 10, the output shaft rotational speed sensor 15, the resolvers 21 and 22, the accelerator position sensor 31, and the like. The engine rotation speed sensor 10 detects the engine rotation speed Ne (the rotation speed of the engine 100). The output shaft rotation speed sensor 15 detects the rotation speed Np of the output shaft 560 as the vehicle speed V. Resolvers 21 and 22 detect first MG rotation speed Nm1 (rotation speed of first MG 200) and second MG rotation speed Nm2 (rotation speed of second MG 400), respectively. The accelerator position sensor 31 detects an accelerator pedal operation amount A (a user's accelerator pedal operation amount). Each of these sensors outputs a detection result to ECU 1000.

  ECU 1000 incorporates a CPU (Central Processing Unit) and a memory (not shown), and executes predetermined arithmetic processing based on information stored in the memory and information from each sensor. ECU 1000 controls each device mounted on vehicle 1 based on the result of the arithmetic processing.

  FIG. 3 is a circuit diagram of an electric system for driving and controlling first MG 200 and second MG 400. This electrical system includes first MG 200, second MG 400, PCU 600, battery 700, SMR 710, and ECU 1000.

  The connection state between the battery 700 and the electric system including the pair of power lines 54 (the positive line 54p and the negative line 54n) is switched by the SMR 710. When SMR 710 is off, battery 700 is disconnected from the electrical system. When SMR 710 is on, battery 700 is connected to the electrical system. The SMR 710 is controlled (ON / OFF) according to a control signal from the ECU 1000. For example, when the user requests activation of the electric system by performing an operation for starting operation, ECU 1000 turns on SMR 710.

PCU 600 includes a converter 610 and inverters 620 and 630.
Converter 610 has a configuration of a general boost chopper circuit configured by a reactor and two switching elements. An antiparallel diode is connected to each switching element.

  Inverters 620 and 630 are connected to converter 610 via a pair of power lines 54 (hereinafter also simply referred to as “power lines 54”). Therefore, inverters 620 and 630 are electrically connected by power line 54. A smoothing capacitor C0 is provided between the positive electrode line 54p and the negative electrode line 54n.

  Inverter 620 is provided between power line 54 and first MG 200. Inverter 620 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm and W-phase arm are connected in parallel. Each of the U-phase arm, V-phase arm and W-phase arm has two switching elements (upper arm and lower arm) connected in series. Each switching element is provided with an antiparallel diode.

  Inverter 630 is provided between power line 54 and second MG 400. Similarly to inverter 620, inverter 630 has a general three-phase inverter configuration. That is, inverter 630 includes upper and lower arms for three phases (U phase, V phase, W phase) and antiparallel diodes provided in each arm.

  A DC voltage between the pair of power lines 54 (DC voltage between the positive electrode line 54p and the negative electrode line 54n, hereinafter also referred to as “system voltage VH”) is detected by the voltage sensor 180. The detection result of voltage sensor 180 is output to ECU 1000.

  Converter 610 performs bidirectional DC voltage conversion between system voltage VH and voltage Vb of battery 700. When power discharged from the battery 700 is supplied to the first MG 200 or the second MG 400, the voltage is boosted by the converter 610. Conversely, when charging the battery 700 with the power generated by the first MG 200 or the second MG 400, the voltage is stepped down by the converter 610.

  Inverter 620 converts system voltage VH into an alternating voltage by turning on and off the switching element. The converted AC voltage is supplied to first MG 200. Inverter 620 converts AC power generated by first MG 200 into DC power.

  Similarly, inverter 630 converts system voltage VH into an alternating voltage and supplies it to second MG 400. Inverter 630 converts AC power generated by second MG 400 into DC power.

  Thus, power line 54 that electrically connects converter 610 and inverters 620 and 630 is configured as a positive and negative bus shared by each inverter 620 and 630. Since power line 54 is electrically connected to both first MG 200 and second MG 400, power generated by one of first MG 200 and second MG 400 can be consumed by the other.

  Therefore, in a state where SMR 710 is on and battery 700 is connected to the electrical system, battery 700 is charged / discharged by power generated from either first MG 200 or second MG 400 or insufficient power. Conversely, when the SMR 710 is in an off state and the battery 700 is disconnected from the electrical system, the battery 700 cannot be used as a power buffer, and thus it is necessary to balance the power balance between the first MG 200 and the second MG 400.

  ECU 1000 drives and controls first MG 200 and second MG 400 by controlling the switching operations of inverters 620 and 630, respectively. Specifically, ECU 1000 sets first MG torque command value T1com and second MG torque command value T2com according to accelerator pedal operation amount A and vehicle speed V, and the actual torque of first MG200 and the actual torque of second MG400 are the first torque, respectively. A switching control signal is output to the inverters 620 and 630 so as to match the 1MG torque command value T1com and the second MG torque command value T2com.

  FIG. 4 is a diagram schematically illustrating the control mode of second MG 400 (that is, the control mode of inverter 630). In vehicle 1 according to the present embodiment, the control mode of inverter 630 is switched to either the PWM control mode or the rectangular control mode.

  In the PWM control mode, either sine wave PWM control or overmodulation PWM control is performed.

  The sine wave PWM control is used as a general PWM control method, and controls the opening and closing of the switching element in each phase arm according to a voltage comparison between a sine wave voltage command value and a carrier wave (carrier signal). As a result, the fundamental wave component of the line voltage (hereinafter also simply referred to as “inverter output voltage”) output from the inverter 630 to the second MG 400 within a certain period becomes a pseudo sine wave. As is well known, in sine wave PWM control, this fundamental wave component amplitude can only be increased to about 0.61 times the inverter input voltage (modulation rate can only be increased to 0.61).

  The overmodulation PWM control performs PWM control similar to the sine wave PWM control after distorting the carrier wave so as to reduce the amplitude. As a result, the modulation rate can be increased to a range of 0.61 to 0.78. Therefore, in a region where PWM control is performed, sine wave PWM control is performed when the vehicle speed is relatively low, and overmodulation PWM control is performed when the vehicle speed is relatively high.

  On the other hand, in the rectangular control mode, rectangular control is performed. In the rectangular control, the switching operation is performed at a single pace within the predetermined period. As a result, the inverter output voltage within the predetermined period becomes a rectangular wave voltage for one pulse. Thereby, rectangular control is inferior to PWM control in control accuracy (control responsiveness), while the modulation rate can be increased to 0.78 and the motor output can be increased.

  Considering the difference in the characteristics of these control modes, the ECU 1000 determines the vehicle operating point determined by the vehicle driving torque (driving torque of the output shaft 560) and the vehicle speed V (the rotational speed Np of the output shaft 560, that is, the second MG rotational speed Nm2). The control mode is selected according to the area to which the belongs.

  FIG. 5 is a diagram illustrating a correspondence relationship between the vehicle operating point and the control mode of the second MG 400 (inverter 630). Schematically, in the region A1 on the lower rotational speed side than the control boundary line L, a PWM control mode with relatively good controllability is selected in order to reduce the torque fluctuation, and on the higher rotational speed side than the control boundary line L. In the area A2, the rectangular control mode is selected in order to improve the output of the second MG 400.

  In the present embodiment, the control boundary line L is set to a different value when the high speed stage Hi is formed and when the low speed stage Lo is formed. That is, as shown in FIG. 2 described above, when the vehicle speed V is the same, the second MG rotation speed Nm2 is lower when the high speed stage Hi is formed than when the low speed stage Lo is formed. Considering this point, the ECU 1000 sets the control boundary line L2 when the high speed stage Hi is formed to be higher than the control boundary line L1 when the low speed stage Lo is formed. Thereby, it is more difficult to shift to the rectangular control mode when the high speed stage Hi is formed than when the low speed stage Lo is formed.

  Next, batteryless travel control will be described. When an abnormality occurs in battery 700 and charging / discharging is prohibited, ECU 1000 performs fail-safe control that causes vehicle 1 to travel in a state where SMR 710 is turned off and battery 700 is disconnected from the electrical system. This fail-safe control is “battery-less traveling control”.

  At the time of batteryless travel control, the battery 700 cannot be used as a power buffer, so it is necessary to balance the power balance between the first MG 200 and the second MG 400. That is, when traveling under battery-less travel control, it is necessary to drive second MG 400 with the power generated by first MG 200, and it is necessary to control the power generation amount of first MG 200 and the power consumption amount of second MG 400 to the same value.

  FIG. 6 is a flowchart showing a processing procedure of ECU 1000 at the time of batteryless travel control.

  In S10, ECU 1000 calculates vehicle request torque Treq according to accelerator pedal operation amount A and vehicle speed V. For example, ECU 1000 stores in advance a map that defines the correspondence relationship between accelerator pedal operation amount A and vehicle speed V and vehicle required torque Treq, and uses this map to correspond to actual accelerator pedal operation amount A and vehicle speed V. The vehicle request torque Treq to be calculated is calculated.

  In S11, ECU 1000 calculates engine required power Pereq from vehicle required torque Treq. More specifically, ECU 1000 calculates the product (= vehicle required power) of vehicle required torque Treq and output shaft rotation speed Np as engine required power Pereq.

  In S12, ECU 1000 calculates an engine rotation speed target value Nereq and an engine torque target value Tereq that satisfy the engine required power Pereq. For example, ECU 1000 sets in advance an optimal engine operation line determined by engine rotational speed Ne and engine torque Te, and using this optimal engine operation line, engine rotational speed target value Nereq and engine torque satisfying engine required power Pereq. A target value Tereq is calculated.

  In S13, ECU 1000 calculates first MG torque target value T1req that is responsible for the reaction force of engine torque Te from engine required power Pereq and engine rotational speed target value Nereq. Assuming that the planetary gear ratio of the power split mechanism 300 is “ρ”, a relational expression represented by T1 = ρ / (1 + ρ) × Te is established from the mechanical relationship between the first MG torque T1 and the engine torque Te. Since the engine torque Te is a value obtained by dividing the engine power Pe by the engine rotational speed Ne, the ECU 1000 calculates the first MG torque target value T1req using the following equation (1).

T1req = ρ / (1 + ρ) × Tereq = ρ / (1 + ρ) × (Pereq / Nereq) (1)
During batteryless travel control, first MG torque target value T1req is set to a negative value (T1req <0) in order to place first MG 200 in a power generation state. As the first MG torque target value T1req is smaller, the torque generated by the first MG 200 due to power generation (hereinafter also referred to as “negative torque of the first MG 200”) increases, and the power generation amount of the first MG 200 increases.

  At S14, ECU 1000 causes second MG so that first MG target power (= target value of power generation amount of first MG 200) and second MG target power (= target value of power consumption of second MG 400) are the same value. A torque target value T2req is calculated. Specifically, ECU 1000 calculates second MG torque target value T2req using the following equation (2).

T2req = (T1req × Nm1) / Nm2 (2)
In S15, ECU 1000 calculates engine torque target value Tereq, first MG torque target value T1req, and second MG torque target value T2req as engine torque command value Tecom, first MG torque command value T1com, and second MG torque command value T2com, respectively. Set to.

  As described above, during the battery-less running control, in order to balance the power balance by the first MG 200 and the second MG 400, each torque command value is set so that the power generation amount of the first MG 200 and the power consumption amount of the second MG 400 become the same value. Is done. However, when the control mode of the second MG 400 is switched to the rectangular control mode with relatively poor controllability, the control accuracy of the second MG torque T2 deteriorates, and as a result, the power generation amount of the first MG 200 and the second MG 400 power consumption match. Otherwise, the inverter output voltage may become unstable.

  In particular, the inverter output voltage becomes unstable because the required vehicle power changes abruptly. Typically, the accelerator is on (accelerator pedal operation amount A> 0) and the accelerator is off (accelerator pedal operation) at a high vehicle speed. (Amount A = 0) is repeated. When the accelerator is turned on, the negative torque of the first MG 200 is increased in order to increase the power generation amount of the first MG 200 (= the output power of the second MG 400). The engine torque Te is increased to prevent a decrease in the engine rotation speed Ne due to the negative torque increase of the first MG 200, but actually, the engine rotation speed Ne temporarily decreases due to a control delay of the engine 100. The first MG rotational speed Nm1 also temporarily decreases with the temporary decrease in the engine rotational speed Ne (see the collinear diagram in FIG. 2). As a result, the power generation amount of the first MG 200 decreases, and in order to balance the power balance, it is necessary to reduce the output power of the second MG 400 by the amount corresponding to the decrease in the power generation amount of the first MG 200, but the controllability is relatively poor. In the rectangular control mode, the output voltage of the second MG 400 is delayed and the system voltage VH is reduced. As a result, the inverter output voltage is reduced. Therefore, if the accelerator on and the accelerator off are repeated at a high vehicle speed, the inverter output voltage is repeatedly lowered and becomes unstable. When the system voltage VH is equal to or lower than a predetermined value, in a vehicle in which fail-safe that causes the inverters 620 and 630 to be in a shutdown state (stopped state) is performed, there is a possibility that the vehicle travel cannot be continued due to a decrease in the system voltage VH.

  Therefore, in the present embodiment, even at the time of high vehicle speed during battery-less traveling control, even if the system voltage VH is increased (hereinafter, also referred to as “VH increase processing”), the rectangular control is temporarily performed. The system voltage VH is prevented from extremely decreasing. Thereby, the inverter output voltage can be stabilized. This is the most characteristic point of the present embodiment.

  FIG. 7 is a functional block diagram of ECU 1000 when performing the VH increase process. Each functional block shown in FIG. 7 may be realized by hardware or software.

  ECU 1000 includes a first determination unit 1010, a second determination unit 1020, a VH increase processing unit 1030, and a switching unit 1040.

The first determination unit 1010 determines whether or not batteryless travel control is being performed.
The switching unit 1040 switches the reference vehicle speed Vsh used for the determination by the second determination unit 1020 according to the gear stage (gear ratio of the transmission 500) formed by the transmission 500. The switching unit 1040 sets the reference vehicle speed Vsh to “Vsh1” when the low speed stage Lo is formed, and sets the reference vehicle speed Vsh to “Vsh2” higher than Vsh1 when the high speed stage Hi whose speed ratio is smaller than the low speed stage Lo is formed. In the present embodiment, the reference vehicle speed Vsh1 when the low speed stage Lo is formed is set to a value on the lowest speed side of the control boundary line L1 when the low speed stage Lo is formed. Further, the reference vehicle speed Vsh2 when the high speed stage Hi is formed is set to a value on the lowest speed side of the control boundary line L2 when the high speed stage Hi is formed (see FIG. 5).

  Since vehicle 1 according to the present embodiment includes transmission 500, the function of switching unit 1040 is effective. However, in a vehicle that does not include a transmission, the function of switching unit 1040 (whether low speed stage Lo or high speed stage Hi is used). The function of switching the reference vehicle speed Vsh accordingly) is not necessary.

  Second determination unit 1020 determines whether vehicle speed V exceeds reference vehicle speed Vsh set by switching unit 1040.

  The VH increase processing unit 1030 performs a VH increase process when the vehicle speed V exceeds the reference vehicle speed Vsh during the battery-less travel control. Specifically, the VH increase processing unit 1030 sets the system voltage target value VHtag to a value that is higher than the normal value by a predetermined voltage. Then, VH increase processing section 1030 controls first MG 200 and second MG 400 (inverters 620 and 630) such that actual system voltage VH becomes system voltage target value VHtag. As described above, when the vehicle speed V exceeds the reference vehicle speed Vsh during the battery-less travel control, the VH increase process is performed, so that the system voltage VH is prevented from being extremely lowered even if the control is shifted to the rectangular control. . As a result, the inverter output voltage can be stabilized.

  On the other hand, when the vehicle-less travel control is being performed but the vehicle speed V is lower than the reference vehicle speed Vsh (that is, when the PWM control is performed instead of the rectangular control), the VH increase processing unit 1030 does not perform the VH increase processing. That is, VH increase processing section 1030 sets system voltage target value VHtag to a normal value, and controls first MG 200 and second MG 400 (inverters 620 and 630) so that actual system voltage VH becomes system voltage target value VHtag. .

  FIG. 8 is a flowchart showing a processing procedure of ECU 1000 for realizing the above-described function.

In S20, ECU 1000 determines whether or not battery-less travel control is being performed.
In S21, ECU 1000 determines whether or not the speed stage formed by transmission 500 is low speed stage Lo.

  When the low speed stage Lo is formed (YES in S21), the ECU 1000 sets the reference vehicle speed Vsh to “Vsh1” (see FIG. 5) in S22, and moves the process to S24. On the other hand, when high speed stage Hi is formed (NO in S21), ECU 1000 sets reference vehicle speed Vsh to “Vsh2” (see FIG. 5) in S23, and the process proceeds to S24. As described above, the functions of S21 to S23 are not necessary in a vehicle that does not include a transmission.

  In S24, ECU 1000 determines whether or not vehicle speed V exceeds reference vehicle speed Vsh.

  If vehicle speed V exceeds reference vehicle speed Vsh (YES in S24), ECU 1000 performs the above-described VH increase process in S25.

  On the other hand, when vehicle speed V is lower than reference vehicle speed Vsh (NO in S24), ECU 1000 ends the process without performing the VH increase process.

  As described above, in the present embodiment, when the battery-less travel control is performed, if the vehicle speed V exceeds the reference vehicle speed Vsh, a process for increasing the system voltage VH is performed. As a result, even if the control is shifted to the rectangular control, the system voltage VH is prevented from being extremely lowered, so that the inverter output voltage can be stabilized.

  In the present embodiment, the VH increase process is executed under the condition of the vehicle speed V. However, the VH increase process may be executed more directly under the condition that “rectangular control is in progress”. That is, in S24 of FIG. 8, instead of determining whether or not the vehicle speed V exceeds the reference vehicle speed Vsh, it may be determined whether or not rectangular control is being performed.

  If the VH increase process is executed on the condition that the controllability is poor and the inverter output voltage is likely to become unstable, the breakdown of the power balance during the rectangular control can be prevented more directly.

  On the other hand, there is a merit that voltage stability can be ensured not only during the rectangular control but also during the overmodulation PWM control by executing the VH increase process under the condition of the vehicle speed V as in the present embodiment. . That is, as the vehicle speed V increases, the control mode is gradually switched to sine wave PWM control, overmodulation PWM control, and rectangular control, but the inverter output voltage is also compared with sine wave PWM control in overmodulation PWM control. The stability controllability of (system voltage VH) is poor. Therefore, by executing the VH increase process under the condition of the vehicle speed V, the voltage can be stabilized in both areas by executing the VH increase process not only in the rectangular control area but also in the overmodulation PWM control area.

  Further, regardless of the vehicle speed V, the VH increase process may be executed on the condition that the batteryless travel control is being performed. In this way, when battery-less traveling control is being performed, the system voltage VH can be increased in advance in preparation for the transition from PWM control to rectangular control. It is effective for stabilizing the voltage.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 vehicle, 10 engine rotational speed sensor, 15 output shaft rotational speed sensor, 21, 22 resolver, 31 accelerator position sensor, 54 power line, 54n negative line, 54p positive line, 82 driving wheel, 100 engine, 180 voltage sensor, 200 1MG, 300 Power split mechanism, 400 2nd MG, 500 Transmission, 560 Output shaft, 531,532 Pinion, 561,562 Brake, 600 PCU, 610 Converter, 620,630 Inverter, 700 Battery, 1000 ECU, 1010 First determination Unit, 1020 second determination unit, 1030 VH increase processing unit, 1040 switching unit.

Claims (5)

A vehicle that travels by rotating an output shaft connected to drive wheels using at least one of the power of an engine and a motor,
A generator for generating electric power using the power of the engine;
A battery configured to be connectable to a pair of power lines that electrically connect the motor and the generator;
A transmission provided between the motor and the output shaft;
A controller for controlling the motor and the generator;
The control device drives the motor by pulse width modulation control when the vehicle speed is less than a threshold value, and when the vehicle speed exceeds the threshold value, the output is improved than the pulse width modulation control, but the controllability Drives the motor with inferior rectangular control,
When the battery is abnormal, the control device disconnects the battery from the pair of power lines, and performs battery-less travel control that drives the motor with the power generated by the generator.
When the vehicle speed exceeds the reference value corresponding to the threshold value when performing the batteryless travel control, the control device causes the voltage between the pair of power lines to be higher than when the vehicle speed is less than the reference value. Controlling the generator and the motor to be higher ,
The control device changes the reference value according to a transmission gear ratio of the transmission . The vehicle includes a first inverter that is provided between the pair of power lines and the generator and drives the generator, and a second inverter that is provided between the pair of power lines and the motor and drives the motor. A power converter including,
The control device controls the power converter so that an actual voltage between the pair of power lines becomes a target voltage,
2. The control device according to claim 1, wherein, when performing the batteryless travel control, when the vehicle speed exceeds the reference value, the target voltage is set to a higher value than when the vehicle speed is less than the reference value. The vehicle described. The transmission forms either a low speed stage and a high speed stage having a lower speed ratio than the low speed stage,
2. The vehicle according to claim 1 , wherein the control device increases the threshold value and the reference value when the high speed stage is formed than when the low speed stage is formed.   The vehicle includes a ring gear coupled to the motor, a sun gear coupled to the generator, a pinion gear engaged with the sun gear and the ring gear, and a carrier coupled to the engine and rotatably supporting the pinion gear. The vehicle according to claim 1, further comprising a planetary gear device including the planetary gear device. A method for controlling a vehicle that travels by rotating an output shaft coupled to a drive wheel using at least one of the power of an engine and a motor,
The vehicle is
A generator for generating electric power using the power of the engine;
A battery configured to be connectable to a pair of power lines that electrically connect the motor and the generator;
A transmission provided between the motor and the output shaft;
A controller for controlling the motor and the generator;
The control method is:
When the vehicle speed is less than the threshold value, the motor is driven by pulse width modulation control. When the vehicle speed exceeds the threshold value, the output is improved compared to the pulse width modulation control but the controllability is inferior. Driving the motor;
When the battery is abnormal, disconnecting the battery from the pair of power lines, and performing batteryless travel control for driving the motor with the power generated by the generator;
When performing the batteryless travel control, when the vehicle speed exceeds a reference value corresponding to the threshold value, the voltage between the pair of power lines is higher than when the vehicle speed is less than the reference value. Controlling the generator;
And a step of changing the reference value according to a transmission gear ratio of the transmission .

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